The proposed work is composed of three separate investigations. 1) To determine which portion of the collagen chains are in intimate contact with mineral in bone, the most accessible regions of the mineralized collagen will be labeled by the reaction with methyl vinyl ketone, decalcified, and the extent of the reaction determined. This derivatized collagen will be subjected to CNBr digestion and the peptides will be separated and analyzed for the percent free lysine after acid hydrolysis. The peptides with the least amount of derivatized lysine should be the sites of intimate contact of mineral and collagen. 2) Poly(Lys-Ala2) and poly (Lys-Ala3) are models of the crosslinking regions of elastin. The epsilon-carbons of the lysyl residues will be oxidized to allysine residues either chemically or using lysyl oxidase. The conformation of the oxidized product will be determined by CD. The polymers alone or in mixtures will be incubated and the crosslinks formed will be determined after reduction with NaBT4. We will attempt to determine if enzymes are required for formation of the desmosines. 3) This project is to determine the structural features of collagen which are required for the binding of blood platelets and the subsequent release reaction. Chemical derivatives of the side-chain groups of polymeric and monomeric collagen will be synthesized. The collagen will then be bound to Sepharose 2B and labeled platelets will be passed through. The extents of binding and release will be determined by a technique developed here. The role of the carbohydrate moieties on collagen will also be determined by careful periodate oxidation after which the extents of degradation of the carbohydrate and hydroxylysyl residues will be measured. The derived collagen will be tested as above for platelet binding and release.